El Niño-induced drought, which is intensified by climate change, can have huge impacts on soil microbial biomass and plant productivity in tropical forests. We tested whether drought-induced turnover of soil microbial biomass can be a potential source of phosphorus (P), the limiting nutrient, for the reproduction of tropical forest trees (mast fruiting). We measured the seasonal variations in soil microbial biomass P and soil solution P concentrations including the periods before and after drought in a dipterocarp forest in Indonesia. Drought resulted in a decrease in soil microbial biomass C, N, and P, followed by a recovery after re-wetting. There was a sharp peak of soil solution P concentrations during the drought. The significant difference between soil microbial biomass P before and after drought amounted to 2.0 kg P ha⁻¹. The potential P release from microbial turnover is not negligible compared to the additional P demand for fruit production (1.0 kg P ha⁻¹) as well as the annual demand for litter production (2.5 kg P ha⁻¹ year⁻¹). In addition to the accumulation of nutrients for several non-fruiting years and their re-distribution in tree biomass, drought-induced microbial turnover can be nutrient subsidies for dipterocarp reproduction in highly-weathered soils.

厄尔尼诺现象引起的干旱因气候变化而加剧，会对热带森林的土壤微生物生物量和植物生产力产生巨大影响。我们测试了干旱引起的土壤微生物生物量周转是否可以成为磷（P）的潜在来源，磷（P）是热带林木繁殖（肥大结果）的限制养分。我们测量了印度尼西亚龙脑香科森林土壤微生物生物量 P 和土壤溶液 P 浓度的季节变化，包括干旱前后的时期。干旱导致土壤微生物生物量C、N和P减少，复湿后又恢复。干旱期间土壤溶液磷浓度出现尖峰。干旱前后土壤微生物量P显着差异达2.0 kg P ha ^-1。与水果生产的额外磷需求（1.0 kg P ha ^-1）以及凋落物生产的年需求（2.5 kg P ha ^-1 年^-1）相比，微生物周转产生的潜在磷释放不可忽略。除了几个非结果年份养分的积累及其在树木生物量中的重新分配之外，干旱引起的微生物周转还可以为强风化土壤中龙脑香科植物的繁殖提供养分补贴。